In the time-of-flight mass spectrometer, charged particles are analyzed by their mass-to-charge ratio which is determined by measuring the time of flight of the charged particles between two given points, e.g. between the ion source and the ion detector.
It is known in the prior art to employ nonmagnetic time-of-flight mass spectrometers comprising a pulsed ion source, a field-free ion drift space and an ion detector, all said elements being disposed on one and the same ion-optical axis. Among the advantages of such mass spectrometers are:
THE POSSIBILITY OF RECORDING A MASS SPECTRUM IN A FEW MICROSECONDS;
THE POSSIBILITY OF PANORAMIC DISPLAY OF THE ENTIRE MASS SPECTRUM AND ANY INDIVIDUAL PARTS THEREOF;
AN UNLIMITED MASS RANGE FOR THE IONS STUDIED;
A RELATIVELY SIMPLE DESIGN.
Such prior art devices, however, have a major deficiency, viz. poor resolution, which cannot be made greater than several hundred for apparatus parameters in conventional practice.
There also exists in the prior art a nonmagnetic time-of-flight mass spectrometer which comprises an analyzer chamber wherein are disposed, on one and the same ion-optical axis, a pulsed ion source, an ion detector and an arrangement making up for the spread in the times of flight through the field-free space of ions of different energies, viz. an ion relfecting system, which is disposed between the ion source and the ion detector on the ion trajectory.
The advantages offered by this latter prior art device are the same as those of the farmer prior art time-of-flight mass spectrometers described hereabove, i.e. speed of action, panoramic display of the entire mass spectrum and any individual parts thereof, and unlimited mass range for the ions studied. In addition, the latter device has high resolution, up to several thousand at half-height of mass peaks. However, the ion-optical axis in such a prior art device is a broken line: two portions of the ion trajectory (from the source to the reflecting system and from the reflecting system to the detector) must in principle be inclined to the axis of the device, whereas the ion packet plane must be invariably perpendicular to the ion-optical axis. Thus, a special deflection system has to be employed, which adds to the complexity of design and requires an increase in the lateral dimensions of the analyzer chamber. Use of this prior art deflection system brings about difficulties in the use of ion beam focusing systems as well as in the procedure of sample introduction in the ion source, what with the unavoidable nearness of the source and the detector. These deficiencies make it practically impossible to develop devices with a drift space of small length.